1. Field of the Invention
The present invention relates to a lower arm mounting structure of a vehicle suspension, and, more particularly, to a lower arm mounting structure which provides two-point support for a lower arm of the vehicle suspension mounted to a sub frame side member.
2. Description of the Related Art
In a conventional lower arm mounting structure, a lower arm of a suspension may include a first rod which is connected to a wheel of a vehicle, a second rod which extends from the first rod in one direction, and is connected to one side of a sub frame side member, and a third rod 108 which extends from the first rod in a direction opposite to the second rod, and is connected to the other side of the sub frame side member.
A first mount may be formed at a terminal end of the first rod to mount the first rod 104 to the wheel. A second mount may be formed at a terminal end of the second rod to mount the second rod to one side of the sub frame side member. A third mount may be formed at a terminal end of the third rod to mount the third rod to the other side of the sub frame side member.
A horizontal through hole through the third mount may be provided at the terminal end of the third rod. A rubber bush is fitted through the hole and thus, the third rod may be fastened to a mounting bracket formed at the other side of the sub frame side member by a bolt which extends through the rubber bush.
In a conventional lower arm, however, slight displacement occurs at the third mount when a lateral reaction force is applied to the third mount during cornering of the vehicle because the rubber bush fitted in the third mount is slightly elastically deformed due to the lateral reaction force. For this reason, excessive displacement occurs at the first mount, thereby causing the body of the vehicle to be inclined.
A sub frame is arranged beneath an engine room of the vehicle. The sub frame supports an engine and a transmission arranged at the top of the sub frame. The sub frame is also connected to the lower arm of the suspension at one side of the sub frame to secure a desired structural rigidity of the vehicle and to achieve an effective load distribution.
The load distribution path established during sharp cornering of the vehicle may be analyzed as follows. Primarily, a lateral reaction force caused by a reaction to turning of the vehicle is transmitted to the lower arm of the sub frame. Secondarily, the transmitted lateral reaction force is exhibited in the form of a torsion generated at openings in a passenger room of the vehicle. Thirdly, the residual lateral reaction force is exhibited in the form of a rear torsion generated at a rear floor of the passenger room, and thus, vibration.
Thus, the rubber bush used to mount the second mount to the sub frame is elastically deformed during cornering of the vehicle, so that the second mount is displaced relative to the sub frame. The displacement of the second mount causes the third mount to be displaced. As a result, an inclination of the vehicle body occurs.